I think the idea of the UK using the Metric System was first discussed in Parliament way back in 1818. But it took joining the EEC in 1973 before any action was taken, even then pragmatism held sway with a mixed system of measurements. Now, we can safely use either. Being initially educated in the Imperial system and then having to use use the Metric one professionally, I can happily switch between both.
The Imperial system is often stated to be "illogical" but it's units can be based on quantities that are easy to comprehend. Yes, the inch is the "width of a thumb", the foot the "length of a foot", a yard the distance between "nose and the end of an outstretched arm" (remember how lengths of material used to be measured?). The mile goes back to the Roman Empire as a measure equal to 1000 strides. The fathom being 6 feet long was around the height of a man. OK, some are less easy to relate to, I never got along with rods, poles and chains![size=78%] [/size]
It's when you combine these units that you often see the value of the Imperial system. Take Stress as an example, I can visualize a value of 80 tons per square inch but the Metric equivalent of 1.3 G Newtons isn't so easy to relate to. This has often been the cause of problems as mistakes don't always "jump out at you" when dealing with very large or small powers of ten.
So, when building my models (or doing other jobs) I'll happily work with inches/feet or millimetres/centimetres, it's usually the materials I'm working with that dictate the units used. But, when discussing or explaining things I try to use both systems, if only to avoid upsetting those wedded to one and only one system of measurement.
Glynn Guest